X86 Assembly/X86 Instructions

These pages will discuss, in detail, the different instructions available in the basic x86 instruction set. For ease, and to decrease the page size, the different instructions will be broken up into groups, and discussed individually.

Some instructions, especially when built for non-Windows platforms (i.e. Unix, Linux, etc.), require the use of suffixes to specify the size of the data which will be the subject of the operation. Some possible suffixes are:

b (byte) = 8 bits

w (word) = 16 bits

l (long) = 32 bits

q (quad) = 64 bits

An example of the usage with the mov instruction on a 32-bit architecture, GAS syntax:

movl$0x000F,%eax# Store the value F into the eax register

On Intel Syntax you don't have to use the suffix. Based on the register name and the used immediate value the compiler knows which data size to use.